Chromium - known to cause lung cancer. It is used in wood treatment, wood preservatives, metal plating and alloys. Those involved in welding have the greatest risk of exposure.
Cresol - acute inhalation can cause throat, nasal and upper respiratory irritation. It is used in disinfectants, wood preservatives and solvents.
Crotonaldehyde - a warning agent in fuel gasses. Experts say it messes up the human immune system. It can also cause chromosomal changes.